function fnCatalog() {
    document.main_form.method = 'POST';
    document.main_form.action = 'catalog.php';
    document.main_form.submit();
}
function fnDetilBarang() {
    document.main_form.method = 'POST';
    document.main_form.action = 'detilBarang.php';
    document.main_form.submit();
}